Global momentum is growing for a new address system, known as IPv6, which promises to vastly expand the pool of unique numbers available for connecting PCs and other devices to the Net. The standard is widely seen as a necessary successor to the current IPv4 system, which some fear could run short of addresses in Asia and Europe within the next few years. But few analysts expect the problem to affect North America and influential U.S. networks any time soon, thanks to unique conditions that will likely guarantee the region a steady supply of IPv4 addresses for years to come. Since fear of an address shortage is the single biggest argument in favor of a switch, the U.S. could stay on the sidelines as the rest of the world wrestles with the upgrade over the coming years, networking experts said.

The U.S. may not see a shortfall because it was granted an enormous number of addresses in the original worldwide allotment. "Asia hits a problem in two or three years time," said Ovum analyst Iain Stevenson. "You won't see similar problems in other regions for four or five years. And in North America you won't see a problem at all." The prospects of a costly Internet address overhaul in the United States is in the spotlight following an endorsement of IPv6 last month from the U.S. Department of Defense (DOD). The $30 billion-a-year agency plans to move all its networks to the new Net address standard by 2008, fueling speculation that the switch--already under way in Japan and other parts of the world--may at last be at hand in the United States.